In reply to Anglesey Pete:
Plas y Brenin charge an arm and a leg for their coaching courses but I know plenty of paddlers who have used them in their early careers.
Why not relate your charges to income ? £100.00 for well paid Yuppy paddlers to £30.00 for UB 40 paddlers ?
The cheap option is joining a club for £10.00 and then tag along their regular trips as I did. 50% of the members have instructors qualifications and some are members of the well ard north west paddlers so you're in good hands !